[RFC] USB: serial: handle disconnect for dtr_rts in core

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Make sure serial-driver dtr_rts is called with disc_mutex held after
checking the disconnected flag.

It does not make sense for usb-serial drivers to manipulate modem
control signals after the device is gone so check for disconnect in usb
serial core.

Not-signed-of-yet-by: Johan Hovold <jhovold@xxxxxxxxx>

---
 drivers/usb/serial/ftdi_sio.c   |   20 +++++++++-----------
 drivers/usb/serial/mct_u232.c   |   23 ++++++++++-------------
 drivers/usb/serial/quatech2.c   |   18 ++++++++----------
 drivers/usb/serial/sierra.c     |    7 +------
 drivers/usb/serial/ssu100.c     |   19 ++++++++-----------
 drivers/usb/serial/usb-serial.c |   10 ++++++++--
 drivers/usb/serial/usb_wwan.c   |    7 +++----
 7 files changed, 47 insertions(+), 57 deletions(-)

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 8c084ea..b49dd8e 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1861,24 +1861,22 @@ static void ftdi_dtr_rts(struct usb_serial_port *port, int on)
 {
 	struct ftdi_private *priv = usb_get_serial_port_data(port);
 
-	mutex_lock(&port->serial->disc_mutex);
-	if (!port->serial->disconnected) {
-		/* Disable flow control */
-		if (!on && usb_control_msg(port->serial->dev,
+	/* Disable flow control */
+	if (!on) {
+		if (usb_control_msg(port->serial->dev,
 			    usb_sndctrlpipe(port->serial->dev, 0),
 			    FTDI_SIO_SET_FLOW_CTRL_REQUEST,
 			    FTDI_SIO_SET_FLOW_CTRL_REQUEST_TYPE,
 			    0, priv->interface, NULL, 0,
 			    WDR_TIMEOUT) < 0) {
-			    dev_err(&port->dev, "error from flowcontrol urb\n");
+			dev_err(&port->dev, "error from flowcontrol urb\n");
 		}
-		/* drop RTS and DTR */
-		if (on)
-			set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
-		else
-			clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
 	}
-	mutex_unlock(&port->serial->disc_mutex);
+	/* drop RTS and DTR */
+	if (on)
+		set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
+	else
+		clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
 }
 
 /*
diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c
index d0ec1aa..e8b526d 100644
--- a/drivers/usb/serial/mct_u232.c
+++ b/drivers/usb/serial/mct_u232.c
@@ -499,19 +499,16 @@ static void mct_u232_dtr_rts(struct usb_serial_port *port, int on)
 	unsigned int control_state;
 	struct mct_u232_private *priv = usb_get_serial_port_data(port);
 
-	mutex_lock(&port->serial->disc_mutex);
-	if (!port->serial->disconnected) {
-		/* drop DTR and RTS */
-		spin_lock_irq(&priv->lock);
-		if (on)
-			priv->control_state |= TIOCM_DTR | TIOCM_RTS;
-		else
-			priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
-		control_state = priv->control_state;
-		spin_unlock_irq(&priv->lock);
-		mct_u232_set_modem_ctrl(port->serial, control_state);
-	}
-	mutex_unlock(&port->serial->disc_mutex);
+	/* drop DTR and RTS */
+	spin_lock_irq(&priv->lock);
+	if (on)
+		priv->control_state |= TIOCM_DTR | TIOCM_RTS;
+	else
+		priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
+	control_state = priv->control_state;
+	spin_unlock_irq(&priv->lock);
+
+	mct_u232_set_modem_ctrl(port->serial, control_state);
 }
 
 static void mct_u232_close(struct usb_serial_port *port)
diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
index 8dd88eb..37a4850 100644
--- a/drivers/usb/serial/quatech2.c
+++ b/drivers/usb/serial/quatech2.c
@@ -968,19 +968,17 @@ static void qt2_dtr_rts(struct usb_serial_port *port, int on)
 	struct usb_device *dev = port->serial->dev;
 	struct qt2_port_private *port_priv = usb_get_serial_port_data(port);
 
-	mutex_lock(&port->serial->disc_mutex);
-	if (!port->serial->disconnected) {
-		/* Disable flow control */
-		if (!on && qt2_setregister(dev, port_priv->device_port,
+	/* Disable flow control */
+	if (!on) {
+		if (qt2_setregister(dev, port_priv->device_port,
 					   UART_MCR, 0) < 0)
 			dev_warn(&port->dev, "error from flowcontrol urb\n");
-		/* drop RTS and DTR */
-		if (on)
-			update_mctrl(port_priv, TIOCM_DTR | TIOCM_RTS, 0);
-		else
-			update_mctrl(port_priv, 0, TIOCM_DTR | TIOCM_RTS);
 	}
-	mutex_unlock(&port->serial->disc_mutex);
+	/* drop RTS and DTR */
+	if (on)
+		update_mctrl(port_priv, TIOCM_DTR | TIOCM_RTS, 0);
+	else
+		update_mctrl(port_priv, 0, TIOCM_DTR | TIOCM_RTS);
 }
 
 static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch)
diff --git a/drivers/usb/serial/sierra.c b/drivers/usb/serial/sierra.c
index ba54a0a..c876bd0 100644
--- a/drivers/usb/serial/sierra.c
+++ b/drivers/usb/serial/sierra.c
@@ -875,12 +875,7 @@ static void sierra_dtr_rts(struct usb_serial_port *port, int on)
 	portdata->rts_state = on;
 	portdata->dtr_state = on;
 
-	if (serial->dev) {
-		mutex_lock(&serial->disc_mutex);
-		if (!serial->disconnected)
-			sierra_send_setup(port);
-		mutex_unlock(&serial->disc_mutex);
-	}
+	sierra_send_setup(port);
 }
 
 static int sierra_startup(struct usb_serial *serial)
diff --git a/drivers/usb/serial/ssu100.c b/drivers/usb/serial/ssu100.c
index 3fee23b..c4409b1 100644
--- a/drivers/usb/serial/ssu100.c
+++ b/drivers/usb/serial/ssu100.c
@@ -505,19 +505,16 @@ static void ssu100_dtr_rts(struct usb_serial_port *port, int on)
 {
 	struct usb_device *dev = port->serial->dev;
 
-	mutex_lock(&port->serial->disc_mutex);
-	if (!port->serial->disconnected) {
-		/* Disable flow control */
-		if (!on &&
-		    ssu100_setregister(dev, 0, UART_MCR, 0) < 0)
+	/* Disable flow control */
+	if (!on) {
+		if (ssu100_setregister(dev, 0, UART_MCR, 0) < 0)
 			dev_err(&port->dev, "error from flowcontrol urb\n");
-		/* drop RTS and DTR */
-		if (on)
-			set_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
-		else
-			clear_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
 	}
-	mutex_unlock(&port->serial->disc_mutex);
+	/* drop RTS and DTR */
+	if (on)
+		set_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
+	else
+		clear_mctrl(dev, TIOCM_DTR | TIOCM_RTS);
 }
 
 static void ssu100_update_msr(struct usb_serial_port *port, u8 msr)
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 6a1b609..60aa1e8 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -686,10 +686,16 @@ static int serial_carrier_raised(struct tty_port *port)
 static void serial_dtr_rts(struct tty_port *port, int on)
 {
 	struct usb_serial_port *p = container_of(port, struct usb_serial_port, port);
-	struct usb_serial_driver *drv = p->serial->type;
+	struct usb_serial *serial = p->serial;
+	struct usb_serial_driver *drv = serial->type;
+
+	if (!drv->dtr_rts)
+		return;
 
-	if (drv->dtr_rts)
+	mutex_lock(&serial->disc_mutex);
+	if (!serial->disconnected)
 		drv->dtr_rts(p, on);
+	mutex_unlock(&serial->disc_mutex);
 }
 
 static const struct tty_port_operations serial_port_ops = {
diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index f35971d..68aa7d4 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -51,12 +51,11 @@ void usb_wwan_dtr_rts(struct usb_serial_port *port, int on)
 		return;
 
 	portdata = usb_get_serial_port_data(port);
-	mutex_lock(&serial->disc_mutex);
+	/* FIXME: locking */
 	portdata->rts_state = on;
 	portdata->dtr_state = on;
-	if (serial->dev)
-		intfdata->send_setup(port);
-	mutex_unlock(&serial->disc_mutex);
+
+	intfdata->send_setup(port);
 }
 EXPORT_SYMBOL(usb_wwan_dtr_rts);
 
-- 
1.7.8.6

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B and H Foto and Electronics Corp.

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